Clear cache on mac
Skype for Business/Lync caches files locally on a MAC to pull information quickly and efficiently. Common reasons you will want to clear Skype for Business cache include:
You can't log in to Skype for Business.
You have issues with Presence.
Your Contact list is out of date.
You cannot search for users in Skype for Business.
Action
Log out and quit Skype for Business.
Go to Finder > press Command+Shift+G > type in ~/Library > delete the following files:
~/Library/Containters > com.microsoft.SkypeForBusiness
~/Library/Application Support > Skype folder
~/Library/Internet Plug-Ins > MeetingJoinPlugin.plugin
~/Library/Logs > LwaTracing
Open Keychain Access from /Applications/Utilities folder.
Delete all keychains starting with Skype For Business.
Note: if you cannot locate the necessary folder under Library, type in the full path in the Finder or Spotlight search.